First off, add bass. I don't think I can hear any. Bass guitars will always make your guitars seem much more powerful. The drums need some humanization, try the humanizer in reaper (highlight notes and hit the H key). The beginning should be very punchy, but the drums aren't quite sticking out in that regards, add a room reverb to it. You could have a mix as high as 40-50 percent with it, my drums reverb (that I apply to the whole kit) is at 45.5%. Don't apply the reverb and listen to the drums solo though, raise it until you hear the presence just begin to stick out in the mix, because its about making the mix sound best, not making instruments sound best on there own, So go with what benefits the mix most. Most drums have a good amount, to being completely saturated in reverb, because it works in the context of the mix.

The dynamic contrast between the thunder and the mix is off, keeping the thunder low in volume will allow the music entering to become a lot more impacting. The guitar tone and playing seem tight enough, so you got that down.

The solo is way loud though, I had to turn my monitors down a good bit, so lower that.

And lastly, if you can, record and mix with a compressor on your master bus. Keep the setting very light, maybe a 2:1 ratio with a 10-15ms attack, and a longer release. This will keep your mix glued together and create a very cohesive feel in the end. And when the mix is done, then you can mess with the compressor further, along with any mastering aspects you might want to do.

Well if it comes to drums I use EZdrummer with Metal Machine expansion. Some of the riffs uses patterns from Metal Machine (ofcourse adjusted), but mostly I write them on my own in midi editor in Cubase.

Hi mate! The track sounds very interesting. I like the different riffs, and the overall feel. Those synth choirs also sound good to me. There are some mixing issues like The Uncreator said but the composition is very promising. Let's see what happens when you add some vocals. Great job!